Absorbent cleaning pad having durable cleaning surface and method of making same

ABSTRACT

A method for forming a cleaning pad body comprising a matrix web formed from binder fibers and a cleaning surface is provided. The method includes depositing a first concentration by weight of binder fibers so as to define the cleaning surface. A second concentration by weight of binder fibers is deposited onto the first concentration by weight of binder fibers, wherein the second concentration by weight of binder fibers is less than the first concentration by weight of binder fibers. The first and second concentrations by weight of binder fibers are bound together to form the matrix web.

This application is a divisional of U.S. Utility patent application Ser.No. 11/240,929, filed on Sep. 30, 2005, which is currently pending andis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an absorbent cleaning pad and to amethod for fabricating the absorbent cleaning pad with a durablecleaning surface.

BACKGROUND OF THE INVENTION

Modern floor cleaning implements employ disposable wipes or cleaningsheets, which are releasably affixed to the head of a mopping implement,and which can conveniently be discarded and replaced after the cleaningsheet is sufficiently soiled. A side of the disposable absorbentcleaning sheet is in contact with a surface to be cleaned.

The cleaning sheet should be of sufficient integrity to withstand thecommon mopping action stress and pressure and exhibit durabilitythroughout one or more mopping sessions. In particular, the cleaningsurface of the cleaning sheet, which endures a significant portion ofthe stress and pressure should be adequately robust to substantiallyresist significant abrasion and deformation.

Various disposable cleaning sheets have been proposed. For example, acleaning pad surface is disclosed in U.S. Pat. No. 6,725,512, whichillustrates a three-dimensional image imparted on the cleaning surfaceof a cleaning pad. The three-dimensional image of the cleaning pad isintended to induce the formation of lather due to pronounced surfaceprojections that come in contact with the soiled surface and provide airpassageways that are parallel to the plane of the substrate. The imagednonwoven fabric is claimed to reduce the potential of fibercontamination at the cleaning surface and is intended to be used in avigorous manner without substantially abrading.

Nevertheless, there continues to be a need for improved cleaning sheetsor cleaning pads.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a method is provided forforming a cleaning pad comprising a matrix web formed from binder fibersand a cleaning surface. The method includes depositing a firstconcentration by weight of binder fibers so as to define the cleaningsurface. A second concentration by weight of binder fibers is depositedonto the first concentration by weight of binder fibers, wherein thesecond concentration by weight of binder fibers is less than the firstconcentration by weight of binder fibers. The first and secondconcentrations by weight of binder fibers are bound together to form thematrix web.

According to another aspect of the invention, another method is providedfor forming a cleaning pad comprising a matrix web formed from binderfibers and a cleaning surface. The method includes depositing a firstportion of substrate comprising binder fibers so as to define thecleaning surface. The first portion of substrate is then densified. Asecond portion of substrate comprising binder fibers is deposited ontothe first portion of substrate. The first and second portions ofsubstrate are bound together to form the matrix web.

According to yet another aspect of the invention, another method isprovided for forming a cleaning pad comprising a matrix web formed frombinder fibers and a cleaning surface. The method includes depositing afirst portion of substrate comprising binder fibers so as to define thecleaning surface. A second portion of substrate comprising binder fibersand non-binder fibers is deposited onto the first portion of substrate,wherein the second portion of substrate comprises a concentration byweight of non-binder fibers greater than a concentration of anynon-binder fibers in the first portion of substrate. The first andsecond portions of substrate are bound together to form the matrix web.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described with referenceto the drawings, of which:

FIG. 1 is a bottom view of an absorbent cleaning pad in accordance withan exemplary embodiment of the present invention;

FIG. 2 is a right side view of the absorbent cleaning pad illustrated inFIG. 1;

FIG. 3 is an end view of the absorbent cleaning pad illustrated in FIG.1;

FIG. 4 is a top view of the absorbent cleaning pad illustrated in FIG.1, including a cut-away portion of the cleaning pad;

FIG. 5 a is a cross-sectional partial end view of an embodiment of aunitized airlaid composite suitable for use in the absorbent cleaningpad illustrated in FIG. 1;

FIG. 5 b is a cross-sectional partial end view of another embodiment ofa unitized airlaid composite suitable for use in the absorbent cleaningpad illustrated in FIG. 1;

FIG. 6 is a schematic, perspective view of an embodiment of a systemthat can be used to form an absorbent cleaning pad according to anaspect of this invention;

FIG. 7 is a schematic, sectional side view of the system illustrated inFIG. 6; and

FIG. 8 is a flow chart illustrating exemplary steps of a process forforming an absorbent cleaning pad according to another aspect of theinvention.

FIGS. 9 through 19 are schematic representations of exemplary systemsthat can be used to form a unitized airlaid composite according toaspects of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention. Also, the embodiments selectedfor illustration in the figures are not shown to scale and are notlimited to the proportions shown.

As used herein, the term “nonwoven web” defines a web having a structureof individual fibers which are interlaid, but not in an ordered oridentifiable manner such as in a woven or knitted web. As defined byINDA, a trade association representing the nonwoven fabrics industry,nonwoven fabrics are generally sheet or web structures bonded togetherby entangling fiber or filaments (and by perforating films)mechanically, thermally or chemically.

Nonwoven webs are formed from many processes, such as, for example,air-laying processes, meltblowing processes, spunbonding processes,coforming processes and bonded carded web processes. The term “airlaidcomposite” implies that a non-woven web is formed by an air-layingprocess.

As used herein, the term “bi-component fiber” or “multi-component fiber”refers to a fiber having multiple components such as fibers comprising acore composed of one material (such as a polymer) that is encased withina sheath composed of a different material (such as another polymer or athermoplastic polymer). Some types of “bi-component” or“multi-component” fibers can be used as binder fibers that can be boundto one another to form a unitized structure. For example, in a polymericfiber, the polymer comprising the sheath often melts at a different,typically lower, temperature than the polymer comprising the core. As aresult, such binder fibers provide thermal bonding due to melting of thesheath polymer, while retaining the desirable strength and fibrousstructure characteristics of the core polymer. As an alternative tousing a binder fiber, fibers are optionally spunbound or otherwiseformed into a nonwoven structure.

As used herein, the term “concentration by weight” is defined as theratio of the weight of one component (e.g. binder fibers) within astructure or a portion of a structure to the weight of all components(e.g. binder fibers and non-binder fibers) within the structure or theportion of the structure. In other words, the concentration by weight ofa component is the weight ratio of that component to all components.

Referring to the overall structure of one exemplary embodiment, FIGS. 1thru 5 a illustrate an absorbent cleaning pad designated generally bythe numeral “110”. Generally, the absorbent cleaning pad 110 has a padbody formed from a unitized airlaid composite and having a cleaningsurface configured for cleaning contact with a surface to be cleaned andan opposite surface configured to be positioned facing a cleaningimplement. The surface cleaning pad also has a backing (e.g., film orfabric) adhered to and substantially covering the opposite surface ofthe pad body and a pair of lofty cuffs adhered to the cleaning surfaceof the pad body.

As an alternative to applying a backing to a surface of the pad body inthe form of a separate component adhered to (or otherwise associatedwith) the pad body, a backing is optionally provided by chemically,mechanically, or thermally modifying a surface of the pad body. Forexample, an agent is optionally applied to the pad body to provide abacking function. In such an embodiment, an agent (e.g., afluoro-chemical compound or a sizing agent or an suitable waterproofingagent) is optionally sprayed, coated, or otherwise applied to a surfaceof the pad body. Alternatively, a layer of hydrophobic fibers ornonwoven can be used to provide a backing function.

An applied agent can provide a surface (or a portion of a surface) ofthe pad body with selected characteristics. For example, the surface orsurface portion can be rendered hydrophobic (to resist or prevent thepassage of fluid) or hydrophilic (to encourage or promote the passage offluid) through the surface or surface portion. In one use, the agentrenders a surface of the pad body hydrophobic to prevent liquid frompassing from within the pad body through the surface. Such a surface isparticularly advantageous for surfaces of a cleaning pad that facetoward a cleaning implement to which it is attached.

More specifically, and according to one embodiment, the exemplaryabsorbent cleaning pad 110 or cleaning sheet is provided with a unitizedairlaid composite 120, supplementary dirt entrapment surfaces in theform of two lofty cuffs 125, a backing layer 140, and two attachmentmembers 145. Each lofty cuff 125 is folded into two equal segments andpositioned along the length “B” of the unitized airlaid composite 120although each cuff is alternatively formed from a single layer ofmaterial. Additional benefits and features of such cuffs are disclosedin U.S. application Ser. No. 11/241,437. A portion of the width of eachlofty cuff 125 is bonded to a cleaning surface or side 152 of theunitized airlaid composite 120 using an adhesive 130. The backing layer140 is adhered to the attachment surface or side 155 of the unitizedairlaid composite 120 using an adhesive 130 and folded around thewidth-wise sides 124 of the unitized airlaid composite 120, therebyenclosing the width-wise sides 124. As discussed previously, the backinglayer 140 is optionally eliminated, and the function of the backinglayer 140 can alternatively be eliminated or provided by applying anagent directly to a surface or a surface portion of the pad body or byotherwise chemically, mechanically, or thermally modifying the surfaceof the pad body.

The unitized airlaid composite 120 of the exemplary embodiment absorbsand retains fluids and/or other matter residing on a soiled surface andmaintains the structural integrity of the cleaning pad 110 during use.Although the cleaning pad body of the exemplary embodiment is formedfrom a unitized airlaid composite 120, the cleaning pad body may beformed from many processes, such as, for example, meltblowing processes,spunbonding processes, foaming processes, coforming processes and bondedcarded web processes. Accordingly, the cleaning pad body is not limitedto a unitized airlaid composite or air-laying process.

Nevertheless, it has been discovered that the optional use of a unitizedairlaid composite to form the cleaning pad body confers numerous,significant advantages. These advantages are especially significant whenthe cleaning pad body is formed from an airlaid composite suitable fordirect contact with the surface to be cleaned according to aspects ofthis invention (e.g., without the need for a layer of materialinterposed between a surface of the airlaid composite and the surface tobe cleaned).

For example, it has been discovered that by using a unitized airlaidstructure for the pad body, in such a way as to eliminate the need for alayer interposed between the airlaid composite and the surface to becleaned (i.e., wherein a surface of the airlaid composite is exposed inthe final product), the expense and complexity associated withconverting processes can be reduced. More specifically, it has beenrecognized that cost and complexity are introduced when layers ofdifferent materials need to be assembled during the process ofconverting raw materials into a finished product. Such assembly requiresmachinery that is configured to synchronize the positioning of webs ofcomponents as they travel continuously along a machine direction. Also,it has been recognized that processes for converting such raw materialsinto a final product are complicated by the fact that raw materials havedifferent strength and stretch characteristics. Accordingly, reducingthe number of raw materials that need to come together to form afinished product in the converting process (or perhaps even eliminatingthe need to assemble any components) sharply reduces the cost andcomplexity associated with converting processes.

Additionally, it has been discovered that the utilization of a unitizedairlaid construction, without supplemental surface-contacting layerspreventing contact between the airlaid composite and a surface to becleaned, also reduces raw material costs. Because raw materials areoften supplied by different companies and may need to be cut toparticular specifications, there is often a waste of material associatedwith the procurement of such materials for use in converting processes.Also, when such materials are purchased from various suppliers orvendors, the overhead (and margin) associated with such suppliers andvendors are added to the cost of the final product.

Additionally, it has been discovered that the use of laminations bondedtogether to form a cleaning pad structure introduces extra costassociated with such lamination materials. More specifically, suchlaminations may require additional raw materials. Accordingly, theelimination of supplemental layers such as laminations has beendiscovered to reduce the cost associated with the cleaning pad product.

The lofty cuffs 125 serve to facilitate the removal of larger soils fromthe surface being cleaned by contacting and trapping the soil particles.The lofty cuffs 125 typically trap soil particles (e.g., dog hair andsimilar objects) that are too large for the airlaid composite 120 totrap.

The backing layer 140 substantially prevents fluid from passing from theunitized airlaid composite 120 to a cleaning implement to which it isattached, to maintain an unsoiled cleaning implement. The backing layer140 also substantially limits airlaid composite absorbent particles fromescaping out of the exposed width-wise sides 124 of the unitized airlaidcomposite 120.

The attachment members 145 provide an attachment mechanism totemporarily couple the absorbent cleaning pad 110 to a floor cleaningimplement, for example. Additional benefits and features of attachmentmechanisms are disclosed in U.S. application Ser. Nos. 11/241,138 and11/240,949. The disclosure of U.S. application Ser. Nos. 11/241,138 and11/240,949 are incorporated herein by reference in their entirety.

Referring still to FIGS. 1 thru 5 a, the cleaning sheet of the exemplaryembodiment is formed from a unitized airlaid nonwoven composite. Theairlaid nonwoven is a highly absorbent, lofty fabric or composite thatis relatively cost competitive with similar weight nonwovens. Theairlaid composite is composed of at least binder fibers and absorbentcomponents such as cellulosic fibers and/or superabsorbent particleswhich are suspended in a web-like arrangement. Other additionalmaterials (e.g., emulsion polymer bonding systems, hotmelt, powder) areoptionally present, and components of the airlaid may be needled orhydroentangled. The exemplary airlaid composite 120 is a singularunitized body providing a cleaning surface or side 152 that is in directcontact with the soiled surface and an opposing attachment surface orside 155 of the absorbent cleaning pad 110 in contact with the cleaningimplement (not shown). By way of non-limiting example, and for purposesof illustration only, the unitized airlaid composite 120 of theexemplary embodiment is optionally provided with a squeeze-out value ofapproximately 50% and an absorbent capacity of at least approximately 28grams/gram, although higher or lower values for squeeze-out andabsorbent capacity are contemplated as well. The squeeze-out value isthe cleaning pad's capacity to retain absorbed fluid, even during thepressures exerted during the cleaning process. However, a certain amountof fluid is advantageously released during use in order to efficientlyclean a surface such as a floor. A test method for determiningsqueeze-out value is provide in U.S. Pat. No. 6,601,261, to Holt et al.

The unitized airlaid composite 120 is optionally capable of retaining350 grams of de-ionized water. As will be described in further detailbelow, the use of a unitized airlaid composite structure to form the padbody of a cleaning pad advantageously allows for better control ofsqueeze-out value. In other words, the structure and composition of theunitized airlaid can be modified in such a way as to increase ordecrease squeeze-out value and to render squeeze-out value morepredictable. This is particularly advantageous when, according toaspects of this invention, the cleaning pad does not include a layer ofmaterial between the pad body and the surface to be cleaned (i.e., wherean exposed surface of the pad body is configured for direct contact witha surface to be cleaned).

The unitized airlaid composite 120 of the exemplary embodiment issubstantially rectangular in shape having a length B and width A.However, the shape of the unitized airlaid composite 120 is not limitedto a rectangular shape, as the unitized airlaid composite may compriseany shape or form.

Referring to FIG. 5 a specifically, a cross-sectional detailed view ofthe unitized airlaid composite 120 of the exemplary embodiment isillustrated. The unitized airlaid composite 120 includes two or morezones, i.e. a proximal zone 121 (located proximal to and defining thecleaning side 152) and a distal zone 122 (located distal from thecleaning side 152 but adjacent to proximal zone 121 on a side oppositethe cleaning side 152). The proximal zone 121 comprises binder fibers(e.g. bi-component fibers) and the distal zone 122 comprises both binderfibers and non-binder fibers such as absorbent components (e.g.cellulosic fibers and/or super absorbent particles). The concentrationby weight and/or the density of binder fiber material in the proximalzone 121 is preferably, but not always, greater than the concentrationby weight and/or the density of binder fiber material in the distal zone122.

The proximal zone 121 is contiguous with (and defines) the cleaning side152 of the unitized airlaid composite 120 that is in contact with thesoiled surface in use. Accordingly, the proximal zone 121 is composed ofa material sufficiently durable such that the proximal zone 121 retainsits integrity during cleaning and abrading actions against the soiledsurface. This characteristic of the unitized airlaid composite 120 isparticularly advantageous when, according to aspects of this invention,an exposed surface of the pad body is positioned for direct contact witha surface to be cleaned. Additionally, when the proximal zone 121 isprovided with the integrity needed to withstand direct contact with thesurface to be cleaned, the cleaning pad can be provided with improvedintegrity or can be provided with comparable integrity (as compared toconventional products) with less material (e.g., by means of theelimination of any layer interposed between the pad body and the surfaceto be cleaned, by the utilization of less material, etc.).

The proximal zone 121 interacts with the soil as it passes over thesoiled surface, loosening and emulsifying tough soils and permittingthem to pass freely into the distal zone 122 of the pad. The proximalzone 121 can facilitate other functions, such as polishing, dusting,scraping, and buffing a surface. In addition to interacting with thesoiled surface, the proximal zone 121 also serves as a fluid acquisitionzone that delivers fluid to the distal zone 122 of the unitized airlaidcomposite 120.

The distal zone 122 is contiguous with and defines the attachment side155 of the unitized airlaid composite 120 that is in contact with thecleaning implement (not shown). The distal zone 122 facilitates thestorage of clean and/or soiled liquid as well as cleaning solutionremoved from the surface being cleaned. The distal zone 122 also filtersand traps the dirt particles in the soiled liquid. In addition tostoring and filtering liquid, the distal zone 122 facilitates therelease of the stored liquid. Accordingly, the dirt particles areretained within the distal zone 122 after the liquid is released fromthe distal zone 122. Additionally, as discussed previously, thesqueeze-out value of the cleaning pad is optionally controlled to retaina sufficient amount of liquid.

The proximal zone 121 may represent approximately five to approximatelyfifty percent or more of the entire thickness of the unitized airlaidcomposite 120. In composite 120, the proximal zone 121 extends from theexterior cleaning surface or side 152 to a depth spaced from side 152.The distal zone 122 extends from the proximal zone 121 to the attachmentsurface or side 155 of the composite 120. The zones 121 and 122 areintegral with one another by virtue of the process used to form thecomposite 120, described in greater detail hereafter.

The unitized airlaid composite 120 is composed of at least binder fibersand absorbent matter such as fluff pulp and a super absorbent polymer(SAP). The relationship between the concentration by weight of binderfibers and the concentration by weight of absorbent matter has an impactupon the tensile strength and the absorbency of the unitized airlaidcomposite 120. As used herein, the term “tensile strength” is defined asthe amount of force a fiber or material web can withstand beforebreaking or permanently deforming. Prior to breaking or permanentlydeforming, the fiber or material web may elastically deform.

The web tensile strength is substantially linearly proportional to theconcentration by weight of binder fibers in the unitized airlaidstructure. Hence, as the percentage by weight of binder fibers increasesrelative to the percentage by weight of absorbent matter in a particularportion of the composite, the tensile strength of the unitized airlaidcomposite increases in that portion. However, it should be noted that asthe percentage by weight of binder fibers increases in a particularportion, the concentration by weight of absorbent matter decreases,thereby reducing the absorbency of the unitized airlaid composite 120 inthat portion. The graph below illustrates the relationship between theunitized airlaid web tensile strength and the percentage of binderfibers within the unitized airlaid structure.

In addition to tensile strength, it has been discovered that anadvantageous characteristic of an airlaid composite used in a pad bodyof a cleaning pad according to aspects of the invention is that theairlaid composite will have sufficient tear strength to withstand theforces encountered during the cleaning process, which may includescraping and other vigorous actions under pressure. For example, forembodiments in which the cleaning surface of the cleaning pad is anexposed surface of airlaid composite, the airlaid composite should beable to withstand forces encountered with rough or irregular cleaningsurfaces without tearing. It is recognized that surfaces to be cleaned(e.g., floors, walls, and other similar surfaces) may include surfacefeatures capable of engaging selected portions of the cleaning pad. If,for example, the head of a nail or screw or staple protrudes from asurface to be cleaned, that surface feature may engage the cleaning padwhile a force of continued movement is applied to the cleaning pad,thereby encouraging a tear in the pad and/or possible linting from zonesof the pad exposed by such a tear.

It has further been discovered that, while maintaining a sufficienttensile strength and a sufficient tear resistance as described infurther detail below, it is also advantageous to maintain a reducedcoefficient of friction between the exposed surfaces of the cleaning padand the surface to be cleaned. In other words, the friction encounteredwhen the cleaning pad is moved in sliding relationship with a surface tobe cleaned is advantageously maintained at an acceptable level in orderto facilitate comfortable use of the cleaning pad. If the coefficient offriction between the cleaning pad and the surface to be cleaned becomestoo great, the effort needed to slide the cleaning pad with respect tothe surface to be cleaned may become unacceptable to users of thecleaning pad. The problems associated with an excessive coefficient offriction are exacerbated when a user of such a pad presses hard toremove stubborn dirt deposits. Details with respect to this coefficientof friction will be described later in greater detail.

The foregoing characteristics of tensile strength, tear resistance, andcoefficient of friction have been discovered to compete with oneanother. It is believed that articles, such as airlaid composites,having increased tensile strength and tear resistance often have anincreased coefficient of friction, while materials having a reducedcoefficient of friction may have compromised tensile strength and tearresistance properties. Accordingly, it has been discovered that acleaning pad having a cleaning surface at least partially defined by anexposed region of a unitized airlaid composite preferably balances thecharacteristics of tensile strength, tear resistance, and coefficient offriction.

According to the exemplary embodiment, to achieve a greaterconcentration by weight of binder fibers in the proximal zone 121, theair-laying apparatus is configured to distribute a greater concentrationby weight of binder fibers at the proximal zone 121, as compared to thedistal zone 122. In another embodiment, the binder fibers of theproximal zone 121 may be compacted or densified to increase the densityof the proximal zone 121. In yet another embodiment, the individualbinder fibers of the proximal zone 121 may have a higher basis weightthan the binder fibers of the distal zone 122, as binder fibers ofhigher basis weight typically exhibit greater tensile strength. Theseexemplary embodiments will be described in further detail with referenceto the airlaid fabrication process.

In the exemplary embodiment illustrated in FIG. 5 a, the web of binderfibers in the proximal zone 121 is of greater concentration by weightthan the web of binder fibers in the distal zone 122. It has beendiscovered that a proximal zone 121 comprising at least a fifty percentgreater concentration by weight of binder fibers than the distal zone122 improves the durability of the unitized airlaid composite. It hasalso been discovered that a proximal zone 121 comprising at least a onehundred percent greater concentration by weight of binder fibers thanthe distal zone 122 further improves the durability of the unitizedairlaid composite.

For example, the composite 120 may have a concentration by weight ofbinder fibers of X % in the distal zone 122 and a concentration byweight of binder fibers in the proximal zone 121 of at least about 1½ X%, or more preferably at least about 2X %, more preferably at leastabout 3X %, and most preferably at least about 4X %. The concentrationsby weight of binder fibers in the proximal and distal zones are selecteddepending on the desired tensile characteristics of the composite andother design considerations.

Cellulosic fibers and superabsorbent polymer (SAP) particles 150 providethe unitized airlaid composite 120 with absorbency and fluid storagecapacity. The SAP particles and cellulosic fibers may either bedisbursed throughout the entire airlaid composite 120 or the distal zone122 of the unitized airlaid composite 120. The SAP particles, inparticular, are optionally zoned in a region of the unitized airlaidcomposite 120. Benefits and features of zoned super absorbent particlesand additional absorbent matter are disclosed in U.S. application Ser.No. 11/240,726, the disclosure of which is incorporated herein byreference.

Regarding the composition of the exemplary embodiment of the nonwovenairlaid composite 120, the binder fibers comprising the unitized airlaidcomposite 120 are bi-component fibers. Bi-component fibers maintaintheir fibrous nature after bonding and are easily dispersed throughoutthe airlaid structure, including the z-direction. The resulting airlaidcomposite is a soft structure with superior wet resilience and strength.

The bi-component fibers within the unitized airlaid composite 120influence the airlaid composite's wet and dry tensile strength. Thevariables which most significantly impact airlaid composite web tensilestrength are bi-component concentration, bi-component fiber denier,bi-component fiber length, bi-component fiber basis weight, thepercentage ratio and configuration of core to sheath components of thefiber, and orientation of the bi-component fiber within the airlaidcomposite. By way of non-limiting example, the denier of thebi-component fiber is optionally up to approximately 4, but morepreferably less than about 3, although fibers of higher and lower denierare contemplated as well. According to one exemplary embodiment, adenier of about 1½ or less is optionally selected. For example, fibershaving a denier of 1.55 are preferred according to one exemplaryembodiment of the invention. The length of the bi-component fiber isapproximately four to approximately six millimeters, although longer andshorter fibers are optionally selected. The basis weight of thebi-component fiber as a percentage of the basis weight of the entireairlaid composite is approximately 10% to approximately 50%, but morepreferably about 15% to about 25%.

Although the binder fibers of the exemplary embodiment are bi-componentfibers, the invention is not limited to bi-component fibers. The binderfibers can be mono-component or multi-component. The binder fibers cancomprise solely naturally occurring fibers, solely synthetic fibers, orany compatible combination of naturally occurring and synthetic fibers.The fibers useful herein can be hydrophilic, hydrophobic or can be acombination of both hydrophilic and hydrophobic fibers. Suitablehydrophilic fibers for use in the present invention include cellulosicfibers, modified cellulosic fibers, cellulose acetate, rayon, polyesterfibers, and other fibers such as hydrophilic nylon. Suitable hydrophilicfibers can also be obtained by hydrophilizing hydrophobic fibers, suchas surfactant-treated or silica-treated thermoplastic fibers derivedfrom, for example, polyolefins such as polyethylene or polypropylene andpolyesters.

Referring to FIG. 5 b, another exemplary embodiment of the unitizedairlaid composite 520 is illustrated. The airlaid composite 520 includesthree zones. This exemplary embodiment provides two cleaning sides 552,located on opposing sides of the airlaid composite 520. This exemplaryembodiment permits the utilization of both sides of the airlaidcomposite 520. After one side of the unitized airlaid composite hassignificantly deteriorated, for example, the user can flip the airlaidcomposite 520 over to employ the opposing unused side of the airlaidcomposite.

The unitized airlaid composite 520 includes two proximal zones 521 and522 and one distal zone 523. The proximal zones 521, 522 comprise binderfibers (e.g. bi-component fibers) and the distal zone 523 comprises bothbinder fibers and absorbent components (e.g. cellulosic fibers and/orsuper absorbent particles). However, the proximal zones 521, 522 mayalso contain absorbent components in another embodiment. Although thethickness of the two proximal zones 521, 522 are shown substantiallyequivalent, the embodiment is not limited to the selected illustration,as one proximal zone may be thicker than the other and/or containdifferent concentrations of fibers.

The composition and structure of several exemplary unitized air laidcomposites are summarized in the following table: Components (gsm)Tensile Tear Zone Fiber Pulp SAP Total Strength Resistance Sample 1(Roll 10-HIGH CAPACITY) 1 50 0 0 50 9538 1044.4 (MD)  2 12.1 76 10.898.9 1064.8 (CD)  3 12.1 76 10.8 98.9 4 12.1 76 10.8 98.9 Totals 86.3228 32.4 346.7 Sample 2 (Roll 12-LOW CAPACITY) 1 40 0 0 40 6411.5 754.5(MD) 2 8.1 50.6 1.3 60 766.5 (CD) 3 8.1 50.6 1.3 60 Totals 56.2 101.22.6 160 Sample 3 (Roll 8-HIGH CAPACITY) 1 50 0 0 50 9608 1244.3 (MD)  212.5 77 10 99.5 1092.6 (CD)  3 12.5 77 10 99.5 4 12.5 77 10 99.5 Totals87.5 231 30 348.5 Sample 4 (Roll 14-LOW CAPACITY) 1 25 0 0 25 4393.4599.5 (MD) 2 0 0 0 0 578.3 (CD) 3 9.1 57.1 1.3 67.5 4 9.1 57.1 1.3 67.5Totals 43.2 114.2 2.6 160 Sample 5 (Roll 3-LOW CAPACITY) 1 30 0 0 308346.5 840.7 (MD) 2 30 0 0 30 812.7 (CD) 3 3.3 20.7 9.33 33.33 4 3.320.7 9.33 33.33 Totals 3.3 20.7 9.33 33.33

The samples (S1 to S5) summarized in the foregoing table are unitizedairlaid composites each having a plurality of zones that together definethe thickness of the composite. Each of the Samples 1 to 5 have a zone(Zone 1) that is configured to be positioned away from a head of acleaning implement (if the cleaning pad is used in conjunction with acleaning implement) or away from the user's hand (if the cleaning pad isto be used by hand). The proximal zone, Zone 1 (and sometimes includingZone 2), is the zone that defines at least a portion of the cleaningsurface of the cleaning pad. Zone 1 therefore defines the surface of theunitized airlaid composite that is exposed for direct contact with thesurface to be cleaned.

The remaining zones (Zones 2-4 of Sample 1, for example) areprogressively spaced from the cleaning surface of the cleaning pad. Eachof the zones of the respective samples represent a portion extendingacross a partial thickness of the unitized airlaid composite. Each ofthese zones are portions or parts of an integral, unitized construction.

Referring specifically to Sample 1 for the purpose of illustration, theunitized airlaid composite of that sample includes four (4) zones (Zones1-4), each of which includes one or more constituents or components. Theamount of each component in each of Zones 1-4 is provided in terms ofthe grams per square meter (gsm) of that component of the resultingunitized airlaid composite. For example, Zone 1 of Sample 1 includes 50gsm of a bonding fiber, 0 gsm of pulp, and 0 gsm of super absorbentpolymer (SAP), thereby providing a total of 50 gsm for Zone 1. In Sample1, the composition of Zones 2-4 are the same, each having the sameamount of bonding fibers (12.1 gsm), pulp (76 gsm), and SAP (10.8 gsm),resulting in a total of 98.9 gsm for each of the Zones 2-4. The totalfor the entire unitized airlaid composite of Sample 1 is therefore 346.7gsm. In part because of the composition of SAP in Sample 1, the totalcapacity to absorb liquid is significant for Sample 1.

It will be noted that Sample 1 has a greater amount of bonding fibers inZone 1 (the zone that at least partially defines the cleaning surface ofthe cleaning pad) as compared to Zones 2-4. In fact, the ratio ofbonding fibers in Zone 1 to the amount of bonding fibers in each ofZones 2-4 is over 4:1.

Referring to the components of Sample 2, Sample 2 has a Zone 1 (at leastpartially defining the cleaning surface of the cleaning pad) having 40gsm of bonding fibers and no pulp and no SAP, thereby providing Zone 1with a total of 40 gsm. Zones 2 and 3 are substantially identical inthat they both have 8.1 gsm of bonding fibers, 50.6 gsm of pulp, and 1.3gsm of SAP, each therefore having a total basis weight of 60 gsm. Theairlaid composite of Sample 2 therefore has a total basis weight of 160gsm, and Sample 2 will therefore be expected to have a lower capacity ascompared to Sample 1 because of the reduced quantity of SAP (and pulp).

As indicated in the foregoing table and mentioned previously, several ofthe samples have lower total basis weights while others have highertotal basis weights. For example, Samples 1 and 3 have basis weights ofabout 350 gsm. Such samples can be considered to have a higher capacity.Other samples, for example Samples 2, 4, and 5, have a total basisweight of about 160 gsm and therefore would be expected to have asignificantly lower capacity.

Lower capacity unitized airlaid composites preferably exhibit a tensilestrength of at least about 2000 grams force (gf), more preferably atleast about 3500 gf. The higher capacity unitized airlaid compositespreferably have a tensile strength of at least about 5000 gf, morepreferably at least about 6500 gf.

Regarding tear strength, lower capacity unitized airlaid compositespreferably have a tear strength exceeding about 300 gf, more preferablymore than about 500 gf. The higher absorbent capacity unitized airlaidcomposites preferably have a tear strength exceeding about 800 gf, morepreferably exceeding about 1000 gf.

The tensile strength tests reported in the foregoing table wereconducted using a tensile test device provided by Instron Corporation ofNorwood, Mass. The test was conducted according to the followingprocedures:

(1) cut airlaid tensile samples at 1 inch wide, 6 inch length;

(2) utilize the Instron Series IX Automated Materials Testing Systemwith the following settings:

-   -   -   (a) 2 inch width distance,        -   (b) 12 inch cross head speed,        -   (c) 5.000 (kgf) full scale load range, and        -   (d) test method Airlaid Tensile 71.

For the tear resistance test, the following procedure is used:

-   -   (1) cut airlaid tear samples at 2 inch width, 7 inch length;    -   (2) use the Instron Series IX automated materials testing system        with the following settings:        -   (a) 1 inch width distance,        -   (b) 20 inch cross head speed,        -   (c) 5.000 (kgf) full scale load range, and        -   (d) Test Method 28 Airlaid Tear.

The following table provides the results of testing performed todetermine the coefficient of friction of Sample 1, both in a dry stateand in a wet state (wet with deionized water): Force Force ReadingReading (After Friction (Final) Zeroing) (669 g Coefficient Test (gf)(gf) Load) of Friction Dry 1 117.9 3 114.9 0.17 2 107.8 7 100.8 0.15 3106.5 2.8 103.7 0.16 4 108.3 4.9 103.4 0.15 5 102.3 4.6 97.7 0.15 6101.7 1.7 100 0.15 7 98.1 3.4 94.7 0.14 8 93.6 4.8 88.8 0.13 9 96.3 0.296.1 0.14 10 96.2 0.2 96 0.14 Average 99.61 0.15 St Dev 6.96 0.01 Wet(Deionized Water) 1 93.8 1.6 92.2 0.14 2 97.8 4.8 93 0.14 3 85.7 2.483.3 0.12 4 98.7 3.6 95.1 0.14 5 77.4 3.2 74.2 0.11 6 80.2 2.8 77.4 0.127 86.2 4.4 81.8 0.12 8 79.4 4.9 74.5 0.11 9 68.8 3.1 65.7 0.10 10 80.55.5 75 0.11 Average 81.22 0.12 St Dev 9.69 0.01

Referring to the foregoing table, Sample 1 has an average, lowcoefficient of friction when dry of about 0.15. When wet with deionizedwater, Sample 1 has an average, low coefficient of friction of about0.12.

As described previously, it is advantageous to maintain a reducedcoefficient of friction between the exposed surfaces of the cleaning padand the surface to be cleaned. This feature helps to manage the effortneeded to slide the cleaning pad with respect to the surface to becleaned, especially when a user of such a pad presses hard to removestubborn dirt deposits. Accordingly, it has been discovered to beadvantageous, pursuant to one aspect of this invention, to configure thecleaning surface of the unitized airlaid composite in such a way as tomaintain an average dry coefficient of friction below about 2.5, morepreferably below about 2.0, and most preferably about 1.5 or less. Ithas been discovered to be advantageous to maintain an average wetcoefficient of friction below about 2.0, more preferably below about1.5, and most preferably about 1.2 or less.

FIGS. 6 and 7 schematically show an example of an airlaid compositeforming system 600 that can be used to form an absorbent cleaning padaccording to one aspect of the invention if the pad includes a unitizedairlaid composite. It is also contemplated that the absorbent cleaningpad is formed with an alternative structure, including any fibrous ornon-fibrous material capable of defining a substrate.

Forming heads 604 and 606 each receives a flow of an air fluidized fibermaterial (e.g., binder fibers, wood pulp, other fibrous materials, orcombination thereof) via supply channels 608. A suction source 614,mounted beneath the perforated moving wire 602, draws air downwardlythrough the perforated moving wire 602. In one embodiment, the binderfiber material is distributed and compacted (by the air flow and/or acompaction roll) over the width of the wire 602 to form a first portionon the surface of the wire 602. The first portion comprises the proximalzone 121. A second forming head (not shown) is provided to distribute asecond portion 616 composed of a mixture of binder fibers and non-binderfibers such as cellulosic fibers onto the first portion. The secondportion 616 comprises a segment of the distal zone 122.

The SAP particles are introduced into the particle dispenser 620 througha tube 618. The particle dispenser 620 is configured to direct (e.g.,spray, sprinkle, release, etc.) the SAP particles onto the perforatedmoving wire 602 above the second portion 616. The SAP particles areeither distributed over a portion of the width and/or length of thesecond portion 616 or distributed over the entire second portion 616.The SAP particles blend and disseminate through the second portion 616and are thereby maintained throughout the entire thickness of theunitized airlaid composite.

A third forming head 606 is provided to distribute a third portion 622of binder and/or cellulosic fibers over the SAP particles and the secondportion 616. The third portion 622 comprises the remaining segment ofthe distal zone 122. Although only two forming heads are illustrated,more forming heads may be required to distribute additional portions ofbinder fiber or cellulosic fiber. Thereafter, the portions are heatedfor a period of time until the binder fibers melt together to form aweb-like structure, i.e., a unitized airlaid composite.

In functional terms, the first portion including binder fibers isoriented toward the cleaning surface and provides structure to theunitized airlaid composite. The second portion 616 including binderfibers and cellulosic fibers is maintained over the first portion andprovides structure, absorbency (storage) and filtration to the unitizedairlaid composite. The SAP particles are maintained over the secondportion 616 to provide additional absorbency and filtration to theunitized airlaid composite. The third portion 622 including binderfibers and cellulosic fibers is maintained over the SAP particles and isoriented toward the cleaning implement. The third portion 622 providesstructure and absorbency to the unitized airlaid composite. The portionscollectively form a unitized airlaid composite according to oneembodiment.

Several ways are contemplated to achieve a greater concentration ordensity of binder fibers within the proximal zone 121 of the airlaidcomposite 120. In one exemplary embodiment, the proximal zone 121 andthe distal zone 122 contain an unequal proportion of binder fibers andabsorbency matter (e.g. cellulosic fiber and/or SAP particles). In thisembodiment, the forming head(s) are configured to distribute a greaterconcentration of binder fibers, relative to the concentration ofabsorbent matter, at the proximal zone 121 relative to the distal zone122. More specifically, the ratio of binder fibers to absorbent matteris higher within the proximal zone 121 than within the distal zone 122.Accordingly, the proximal zone 121 contains a greater concentration ofbinder fibers.

In another exemplary embodiment, the forming head(s) are configured todistribute a greater concentration of binder fibers at the proximal zone121 of the unitized airlaid composite, similar to the previousembodiment. The fibers are subsequently heated for a period of timeuntil the binder fibers melt together to form a unitized airlaidcomposite 120. To further increase the concentration of binder fibers atthe proximal zone 121, the entire formed airlaid composite 120 iscompressed. Under an applied compressive load, the binder fibers exhibitgreater permanent deformation than the more resilient cellulosic fibers.Accordingly, since the proximal zone 121 maintains a greaterconcentration of binder fibers, the proximal zone 121 is permanentlycompacted more than the distal zone 122. In other words, followingcompaction, the proximal zone 121 exhibits greater permanent deformationthan the distal zone 122, by virtue of the relative concentrations ofbinder fibers and cellulosic fibers within each zone. Therefore, as aresult of the compaction process (or other manipulations such as achange in the airflow of the through air dryer), the concentration ofbinder fibers within the proximal zone 121 is greater than theconcentration of binder fibers within the distal zone 122.

In yet another exemplary embodiment, as an alternative to compressingthe entire airlaid composite to achieve a greater concentration ofbinder fibers at the proximal zone 121, the proximal zone 121 may beindependently compacted prior to heating the fiber deposits. Generally,as the binder fibers are deposited over the surface of the perforatedmoving wire 602, gaps are inherently formed between the randomlydistributed binder fibers. A compaction roller is positioned to lightlycompress the portion of binder fibers, thereby reducing the gaps betweenthe binder fibers and increasing the density of the subsequent weblayer. More specifically, in this exemplary embodiment the portion ofbinder fibers comprising the proximal zone 121 is compacted. Followingcompaction of the proximal zone 121, a subsequent portion of binderfibers and cellulosic fibers (comprising the distal zone 122) isdistributed over the portion of binder fibers comprising the proximalzone 121. The portions are then heated for a period of time until thebinder fibers melt together to form a unitized airlaid composite,wherein the density of the proximal zone 121 is greater than the densityof the distal zone 122. It should be apparent that compaction roller(s)may be positioned after any one of the forming heads in this embodiment.

In still another exemplary embodiment, to increase the concentration ofbinder fibers at the proximal zone 121 relative to the concentration ofbinder fibers at the distal zone 122, the forming heads 604 and 606distribute binder fibers of different basis weights. Accordingly, theproximal zone 121 includes binder fibers of greater basis weight thanthe distal zone 122. Therefore, as binder fiber webs of higher basisweight exhibit greater tensile strength, the proximal zone 121 isrendered more durable than the distal zone 122 of the unitized airlaidcomposite 120.

FIG. 8 is a flow chart 800 of exemplary steps for fabricating a unitizedairlaid composite in accordance with one embodiment of the presentinvention. Block 802 illustrates the step of depositing a firstconcentration of binder fibers so as to define a cleaning surface. Block804 illustrates the step of depositing a second concentration of binderfibers and cellulosic fibers onto the first concentration of binderfibers, wherein the second concentration of binder fibers is less thanthe first concentration of binder fibers to form an absorbency andfiltration zone. Block 806 illustrates the optional step of depositingan additional concentration of binder fibers and cellulosic fibers ontothe second concentration of binder fibers to further construct theabsorbency and filtration zone. Block 808 illustrates the final step ofbonding the first and second concentrations of binder fibers together toform a web structure, thereby providing a cleaning surface with improvedintegrity.

The figures described below demonstrate exemplary ways in whichcompression can be varied using compression rolls positioned between theforming heads. They also illustrate possibilities for incorporatingother materials, such as spunbond webs, meltblown webs, or otherspunmelt systems into an airlaid system.

Referring now to FIGS. 9 through 19, schematic representations areprovided for exemplary systems that can be used to form a unitizedairlaid composite according to aspects of this invention. Specifically,FIGS. 9 through 19 provide side schematic views of exemplary webs andcomplimentary web-forming systems in such a way as to show how zones ofunitized airlaid composites build while moving through respectiveweb-forming systems. The zones of the exemplary webs are not depicted toany particular proportion or scale, but are instead shown schematicallyfor purposes of illustration only. Also, because of the mixing andblending of fibers between the zones of a unitized airlaid structurethat occurs during the web-forming process, the zones are not distinctas depicted in the figures but are instead integrated with one anotherso as to form a cohesive structure.

Generally, each of the web-forming systems illustrated in FIGS. 9through 19 includes a machine having a conveyor surface including a wirescreen on which the web of the airlaid composite is formed.Fiber-introducing heads are positioned above the wire screen in order todeliver components of the airlaid composite to the screen in acontrolled manner. The fiber-introducing heads are configured tointroduce the same or different fibers in any combination, as depictedschematically in FIGS. 9 through 19 by cross-hatching. For example, twoor more or all of the heads can introduce the same fibers or fibermixture, or all or some of the heads can introduce different fibers orfiber mixtures.

Rolls are also provided in order to selectively modify the web as itpasses through the system. The schematic representation of the resultingweb of the unitized airlaid composite (juxtaposed below the machine ineach of FIGS. 9 through 19) shows the web portions provided by each ofthe heads as those portions build to form the web of the unitizedairlaid composite along the machine direction (MD). Again, the webportions are integrated in actual airlaid systems as opposed to thedistinct zones depicted schematically in FIGS. 9 through 19 for purposesof illustration.

Referring specifically to FIG. 9, one exemplary system utilizes amachine 1004 a to form a web of an airlaid composite 1000 a. The machine1004 a includes a conveyor mechanism 1006 that supports a wire screen1020 on which the components of the airlaid composites are deposited. Apair of upstream rolls 1008 and a pair of downstream rolls 1010 areprovided in such a way that the wire screen 1020 passes between eachpair of rolls 1008 and 1010. Plural heads are provided above the wirescreen 1020 along the length of the machine 1004 a. Specifically,machine 1004 a includes four (4) heads, including a first head 1012, asecond head 1014, a third head 1016, and a fourth head 1018.

First and second heads 1012 and 1014 are positioned upstream from theupstream rolls 1008, and third and fourth heads 1016, 1018 arepositioned downstream from upstream rolls 1008 and upstream fromdownstream rolls 1010. The upstream and downstream rolls 1008 and 1010are optionally utilized as compression rolls, and the distance betweeneach pair of rolls 1008 and 1010 is adjustable as will become clear inconnection with the description of FIGS. 10 through 19.

The machine 1004 a illustrated in FIG. 9 is a 4-head airlaid machineshown to have heads 1012, 1014, 1016 and 1018 feeding substantiallyequal amounts of the same fiber composition. Alternatively, one or moreof heads 1012, 1014, 1016 and 1018 optionally feed substantiallydifferent amounts of fibers or feed substantially different fibers orfiber compositions. As illustrated in FIG. 9, the machine 1004 a doesnot utilize upstream and downstream rolls 1008 and 1010 as compressionrolls (i.e., the distance between the rolls 1008 and 1010 is maintainedso as to eliminate or minimize compression of the web passing betweenthem). Accordingly, the machine 1004 a is configured to yield arelatively thick fabric having a substantially constant density.

Referring now to FIG. 10, the exemplary system shown includes a machine1004 b used to form a web 1000 b. The machine 1004 b is configured toutilize the upstream rolls 1008 as compression rolls while thedownstream rolls 1010 are not so utilized. Accordingly, the machine 1004b is configured to form a variable density fabric because the zonesintroduced by first and second heads 1012 and 1014 are compressed byupstream rolls 1008, thereby increasing the density of those zones,while the zones deposited by third and fourth heads 1016 and 1018 arenot densified because the downstream rolls 1010 are spaced so as tominimize or eliminate any compression of the zones deposited by thoseheads 1016 and 1018.

Referring next to FIG. 11, the illustrated system includes a machine1004 c used to form a unitized airlaid 1000 c. In this system, both theupstream rolls 1008 and downstream rolls 1010 are utilized ascompression rolls, thereby yielding a thinned web of fabric having asubstantially constant density.

Referring now to FIG. 12, which illustrates a machine 1004 d used toform a web 1000 d, only the downstream rolls 1010 are utilized ascompression rolls (upstream rolls 1008 are not so utilized).Accordingly, machine 1004 d provides for an overall compression of theweb, thereby yielding a thinned fabric of substantially constantdensity, similar in respects to the web 1000 c formed according to thesystem illustrated in FIG. 11.

Referring now to FIG. 13, a machine 1004 e is used to form a web 1000 e.Machine 1004 e utilizes both the upstream rolls 1008 and the downstreamrolls 1010 as compression rolls but with varying degrees of compression.More specifically, upstream rolls 1008 are utilized as compression rollswhile downstream rolls 1010 are provided for partial compression.Accordingly, machine 1004 e yields a gradient density web (asillustrated schematically by the relative thicknesses of the zones ofthe web 1000 e), but the web 1000 e differs from the web 1000 b shown inFIG. 10 and the web 1000 c shown in FIG. 11 with respect to thethickness and densities of zones in the web 1000 e (e.g., the top twozones of the respective webs).

Referring to FIG. 14, a machine 1004 f forms a web 1000 f that issimilar to the web 1000 e illustrated in FIG. 13. Web 1000 f differsfrom web 1000 e in the degree of compression provided by downstreamrolls 1010, thereby yielding thicker zones of material deposited via thethird and fourth heads 1016 and 1018.

Referring now to FIG. 15, a machine 1004 g yields a web 1000 g. Thesystem illustrated in FIG. 15 is similar to that illustrated in FIG. 12except that a resilient fiber is introduced through one of the heads.Specifically, a resilient fiber (e.g., a polyester fiber) is introducedto the web via the third head 1016, wherein the fiber introduced viahead 1016 differs from that introduced via heads 1012, 1014, and 1018 atleast in terms of its resiliency. Because of the resiliency of the fiberintroduced through the third head 1016, the zone thus produced tends to“bounce back” to or toward its original shape after passing throughdownstream rolls 1010, thereby yielding a more bulky and lower densitycentral zone surrounded by substantially thinner zones. Such a zone isoptionally provided at any location across the thickness of the web,including top and bottom zones of the web.

FIGS. 16 through 19 illustrate systems that differ from thoseillustrated in FIGS. 9 through 15 in that one or more separate rawmaterial components are introduced into the web by the machine. Theseparate component is optionally a pre-formed web of material such as ameltblown or spunbonded web. Preferably, the separate component isformed in situ to reduce manufacturing costs. A wide variety of othermaterials are contemplated as well.

Referring to FIG. 16, a machine 1004 h is used to form a web 1000 h thatincludes a web of material between adjacent zones of the web 1000 hformed through the second and third heads 1014 and 1016. Morespecifically, a mechanism is provided in machine 1004 h to introduce aweb at a location between the second head 1014 and third head 1016,thereby interposing the web material between the zones of the web 1000 hformed by the second head 1014 and third head 1016. Accordingly, theresulting web 1000 h is similar to the web 1000 a formed by the machine1004 a (FIG. 9), except that an additional web material has beenintroduced into the web 1000 h between zones of the web 1000 h.

Referring to FIG. 17, a machine 1004 i produces a web 1000 i. Web 1000 iis similar to web 1000 b (FIG. 10) in that the upstream rolls 1008 areutilized as compression rolls to compress the first two zones depositedby means of first head 1012 and second head 1014. Web 1000 i is alsosimilar to web 1000 h (FIG. 16) in that separate web material isintroduced between the zones deposited by the second and third heads1014 and 1016.

Referring to FIG. 18, a machine 1004 j is used to form a web 1000 j. Web1000 j is similar to web 1000 f (FIG. 14) in terms of compression ratiosand similar to web 1000 h (FIG. 16) in terms of the introduction of aseparate web composite.

Referring now to FIG. 19, a machine 1004 k is used to form a web 1000 k.The schematic illustration provided in FIG. 19 demonstrates thatmultiple components (the same or different components) can be providedvia heads positioned between the airlaid forming heads. For example,heads can be provided for the introduction of web materials (e.g.,spunbonded or meltblown materials or films) at one or any combination oflocations upstream and downstream of the heads 1012, 1014, 1016 and1018. In machine 1004k, such supplemental heads are provided upstream offirst head 1012, between first head 1012 and second head 1014, betweensecond head 1014 and third head 1016, between third head 1016 and fourthhead 1018, and downstream from fourth head 1018 and upstream ofdownstream rolls 1010. Any combination of such supplemental heads can beutilized, and such heads can be used to introduce the same or differentcomponents in any combination. Also, although not shown in FIG. 19, theupstream rolls 1008 and downstream rolls 1010 can be utilized in anycombination as compression rolls in order to compress selected zones ofthe resulting web 1000 k.

It is also contemplated that an article is optionally produced byforming a unitized airlaid composite directly onto a substrate. Forexample, an article such as a cleaning pad is optionally produced byforming a unitized airlaid composite directly onto a porous substratesuch as a light weight spunbond or other suitable substrate.

Although examples of unitized airlaid composite forming systems areillustrated in the figures, together with descriptions of possiblemodifications or variations of the illustrated systems, this inventionis not limited to the particular airlaid composite forming systemsselected for illustration in the figures, and this invention is notlimited to an absorbent pad having a unitized airlaid structure. Otherairlaid forming systems and other pad-producing processes arecontemplated as well.

For example, an exemplary airlaid machine is available for use atMarketing Technology Service, Inc. of Kalamazoo, Mich. Additionally,airlaid systems are available through MJ Fibretech of Hörstens, Denmarkand Dan-Web of Aarhus, Denmark. Further, an exemplary airlaid process isdisclosed in PCT International Publication No. WO 2004/097097 of Dan-WebHolding A/S, which is incorporated herein by reference.

Independent of the particulars of the system used to form an airlaidstructure, unitized airlaid structures according to aspects of thisinvention exhibit performance characteristics comparable to, orexceeding, those of products made by other processes such as those usedfor laminating multiple fabrics. Additionally, benefits are achieved byutilizing a unitized airlaid structure because it reduces costsassociated with lamination, including costs from converting waste andlost manufacturing efficiency from down time caused by the complexity ofthe lamination process. It is believed that converting losses of about5% or more, and perhaps as much as 15% or more, are associated withlamination processes. Also, lamination speeds may be limited bydifferent stretch, neck-in and tensile strengths of the fabrics to becombined. And there are also costs associated with the laminationadhesive setup and cleanup. In addition, there may be a reduction inoverall loft of the fabric (higher density) in a laminated structure,which may be undesirable.

Lamination processes may require storage of various, different rollgoods and associated quality control, multiple roll good vendors, andthe cost of shipping, delivering, testing and certifying the roll goods.Also, each fabric incorporates its own material waste problems as aresult of its own manufacturing process.

With an airlaid process according to aspects of this invention, avariety of strength and surface textures can be achieved based onselection of fibers, forming wires, resins and compression strategies.By employing plural forming heads and separate fiber feeds, for example,maximum flexibility is provided in the product design. For example,functional surfaces can be provided with unique characteristics ascompared to internal regions of the airlaid composite. In exemplaryembodiments, more expensive fiber zones can be positioned adjacentcheaper inner ingredients.

Additionally, airlaid fibers are optionally deposited on top ofpre-existing fabrics, e.g. a spunbond or hydroentangled web. With suchconstructions, the stability of the web being formed should bemonitored, including such properties as stretch, shrinkage and itsability to be bonded at the preferred temperatures. Additionalfunctionality is optionally added to the unitized airlaid structure byusing spray emulsion polymer adhesive techniques to add such things ascolor, odor reduction, and scrubby surfaces, for example.

Another advantage of unitized airlaid webs is the substantiallynon-directional nature of the webs produced, where tensile strength inthe machine direction MD and cross direction CD is approximately thesame. This is not the case, for example, with carding or spunbonding,which tend to show substantial directionality. Accordingly, suchdirectional alternatives would require higher amounts of material toprovide adequate strength. Although a unitized airlaid system exhibitsadvantages as compared to such other forming systems and structures,such other systems (including lamination) are within the scope of thisinvention especially when used in conjunction with airlaid systems. Itis recognized that some materials (e.g., spunbond webs) are ubiquitousand inexpensive, and therefore such materials may be beneficially used,preferably in conjunction with airlaid unitized structures.

While preferred embodiments of the invention have been shown anddescribed herein, it will be understood that such embodiments areprovided by way of example only. Numerous variations, changes andsubstitutions will occur to those skilled in the art without departingfrom the spirit of the invention. Accordingly, it is intended that theappended claims cover all such variations as fall within the spirit andscope of the invention. Also, the embodiments selected for illustrationin the figures are not shown to scale and are not limited to theproportions shown. Finally, though the foregoing description relatesprimarily to the field of disposable floor mops for purposes ofillustration, the benefits conferred by this invention are alsoapplicable in other fields including, for example, two-sided wipes,unitized filtration media, automotive applications (e.g., filters andfabrics for noise reduction), insulation (e.g., sound and thermalinsulation), aerospace composites, and specialty packaging (e.g., forcushioning or absorbent properties). Other applications are contemplatedas well.

1. In a cleaning pad comprising a matrix web formed from binder fibersand a cleaning surface, a method of forming the cleaning pad comprisingthe steps of: depositing a first concentration by weight of binderfibers so as to at least partially define the cleaning surface;depositing a second concentration by weight of binder fibers, whereinthe second concentration by weight of binder fibers is less than thefirst concentration by weight of binder fibers; and bonding the binderfibers to form the matrix web.
 2. The method of claim 1, wherein saidsecond depositing step further comprises depositing cellulosic fibers.3. The method of claim 1, wherein said second depositing step furthercomprises depositing superabsorbent polymer particles.
 4. The method ofclaim 1, wherein said first concentration by weight of binder fibers isat least about 50 percent greater than said second concentration byweight of binder fibers.
 5. The method of claim 1, wherein said firstconcentration by weight of binder fibers is at least about 100 percentgreater than said second concentration by weight of binder fibers. 6.The method of claim 1, further comprising the step of depositing a thirdconcentration by weight of binder fibers so as to define a secondcleaning surface, wherein the third concentration by weight of binderfibers is greater than the second concentration by weight of binderfibers.
 7. In a cleaning pad comprising a matrix web formed from binderfibers and a cleaning surface, a method of forming the cleaning padcomprising the steps of: depositing a first portion of substratecomprising binder fibers so as to define the cleaning surface;densifying the first portion of substrate; depositing a second portionof substrate comprising binder fibers onto the first portion ofsubstrate; and bonding the first and second portions of substrate toform the matrix web.
 8. The method of claim 7, wherein said seconddepositing step further comprises depositing superabsorbent polymerparticles onto the first portion of substrate.
 9. The method of claim 7,wherein a concentration by weight of binder fibers in the first portionof substrate is greater than a concentration by weight of binder fibersin the second portion of substrate.
 10. The method of claim 7, wherein aconcentration by weight of binder fibers in the first portion ofsubstrate is substantially the same as a concentration by weight ofbinder fibers in the second portion of substrate.
 11. In a cleaning padcomprising a matrix web formed from binder fibers and a cleaningsurface, a method of forming the cleaning pad comprising the steps of:depositing a first portion of substrate comprising binder fibers so asto define the cleaning surface; depositing a second portion of substratecomprising binder fibers and non-binder fibers onto the first portion ofsubstrate, wherein the second portion of substrate comprises aconcentration by weight of non-binder fibers greater than aconcentration of any non-binder fibers in the first portion ofsubstrate; and bonding the first and second portions of substrate toform the matrix web.
 12. The method of claim 11, wherein said firstdepositing step comprises depositing a mixture of non-binder fibers andbinder fibers.
 13. The method of claim 12, wherein said first depositingstep comprises depositing a mixture of cellulosic fibers and binderfibers.
 14. The method of claim 11, wherein said second depositing stepcomprises depositing binder fibers and cellulosic fibers.
 15. The methodof claim 11, further comprising the step of depositing superabsorbentpolymer particles.
 16. The method of claim 11, further comprising thestep of densifying the matrix web.